Construction and earth-moving machines are often propelled by continuous tracks. Such machines may be used to move materials such as soil, rock, gravel, sand, asphalt, and the like during the construction or maintenance of paved surfaces, building sites, landscapes, mines, or other areas. For example, track type tractors and excavators propelled by continuous track may be used to excavate earth, transport earth and/or building materials, smooth and grade surfaces, and demolish old structures. Typically, such machines include a chassis which supports an engine and an operator cab. An undercarriage supports the chassis and includes a pair of continuous track drives. A continuous track drive may include a continuous track supported by undercarriage track rollers and a toothed drive wheel. A continuous track may include links, pins and bushings connecting the links, and a master link. A master link may have a pin section and a bushing section that may be bolted together. Bolting the pin and bushing sections together may make a loop of the pin-connected links that may circumscribe and mate with the toothed drive wheel and undercarriage track rollers, thus forming the continuous track.
During a work cycle, the master link may be subjected to large tension forces and the master link bolts may correspondingly be subjected to large shear forces. Also during a work cycle, the pin and bushing sections of the master link may move relative to each other. For instance, when moving a large load with a track type tractor, the master link must accept a tension force exerted by the toothed drive wheel large enough to displace the machine and the load while the pin and bushing sections flex over uneven terrain. Relative movement combined with such large tension forces may eventually fatigue and subsequently destroy the master link. This situation may result in a work stoppage, further damage to the machine, or otherwise disrupt the worksite. Otherwise, master links may be monitored and preventively removed from the machine before they become fatigued, sometimes resulting in a work stoppage when performing the preventive maintenance. A broken master link may also strand the machine, thus requiring another machine to move the disabled machine to a repair site.
Master links with some relative movement limiting features are available. Such master links are often arranged with a plurality of mating teeth. More specifically, the pin and bushing sections are each equipped with precisely machined mating teeth to increase the engagement surface area between the pin and bushing sections. However, these efforts to provide more engagement surface area between the pin and bushing sections by precisely machining the mating teeth have been found largely lacking. It has been generally found that despite having multiple precision-machined teeth, only thin portions of each tooth engage with a corresponding tooth. In U.S. Pat. No. 8,420,972, Cho shows one example of an existing strategy for attempting to increase engagement surface area.
It can therefore be seen that improvements in the arrangement and manufacture of the master link and associated structures are desired.